If a poison expires, is it no longer poison, or is it more poisonous?

Aluminum reacts with chlorine gas to form aluminum chloride via the following reaction: 2al(s)+3cl2(g)→2alcl3(s) what is the maximum mass of aluminum chloride that can be formed when reacting 32.0 g of aluminum with 37.0 g of chlorine? express your answer to three significant figures and include the appropriate units.

Why does his teacher ask him to balance the equation by including the correct coefficient

What is true for a substance that releases energy